Printing apparatus

ABSTRACT

A printing apparatus includes a color measurement portion which applies a spot of light to a color chart in which a plurality of patches are arranged in the X direction and in the Y direction, and measures a color of each of the plurality of patches using reflected light from the spot, a carriage that includes the color measurement portion mounted thereon, and a moving mechanism which relatively moves the carriage with respect to the color chart in the X direction, and a width of each of the plurality of patches in the X direction is obtained using a predetermined expression.

BACKGROUND

1. Technical Field

The present invention relates to a printing apparatus.

2. Related Art

A technology is known in which a printing apparatus prints a color chartas an aggregation of multiple patches and measures a color of each ofthe patches in the color chart using a color measurement portion. Inthis technology, there is a case in which a size of the patch in thecolor chart affects a result of the measured color. For example, in acase in which the size of patch is small, it is not easy to purelyobtain only the color of the patch as a target to be measured. On theother hand, in a case in which the size of the patch is large, printingof the color chart takes a long time, and loss of ink or paper is alsoincreased.

Here, a technology is known in which printing is performed many times bychanging a size of a target patch, a color of the printed patch ismeasured, and the smallest (optimum) size of the target patch isdetermined based on an obtained value of the measured color, or the like(refer to JP-A-2010-201845).

However, in the above described technology, when the color of the patchis measured by forming the optimum size of the patch, patches havingvarious sizes need to be printed many times, therefore, there areproblems in that a loss amount of the ink is increased, printing takes along time, and the like.

SUMMARY

An advantage of some aspects of the invention is to provide a technologyfor solving the problems of an increase of the loss amount of the ink,taking a long time for printing, and the like when measuring the colorthereof.

A printing apparatus of an aspect of the invention includes a printingportion that prints a color chart in which a plurality of patches arearranged in a first direction and in a second direction different fromthe first direction, a color measurement portion that applies a spot oflight to the color chart, and measures a color of each of the pluralityof the patches using reflected light from the spot, a carriage thatincludes the printing portion and the color measurement portion mountedthereon, and a relative movement portion that relatively moves thecarriage with respect to the color chart, in which a width Wp (m) in thefirst direction in each of the plurality of the patches is expressedusing an expression as follows:

Wp=D+{(D·Tm/Tnl)·(W−D)}^(1/2)

Here, D is a width (m) of the spot in the first direction, Tm is a time(seconds) necessary for measuring the color of one of the plurality ofpatches by relatively moving the carriage in the first direction withrespect to the color chart, Tnl is a time (seconds) necessary for thecarriage to relatively move a distance of one row in the seconddirection with respect to the plurality of patches, and W is a width (m)of the color chart in the first direction.

According to the printing apparatus of the aspect, the width Wp of thepatch in the first direction is calculated using the expression withrespect to values of various components, a process in which the width ofthe patch is measured based on an actual result of measured colors isnot needed. For this reason, it is possible that that a region necessaryfor forming the color chart is reduced, loss amount of the ink isreduced, and manufacturing time is minimized.

Moreover, as described later, the width Wp is not limited to the abovedescribed expression, and it can be acceptable as long as the width W isapproximately within the value +10% or smaller which is expressed usingthe expression.

In the printing apparatus according to the aspect, the color measurementportion may disperse a plurality of wavelengths of the light inchronological order, further, in this configuration, the colormeasurement portion may receive the dispersed light using one lightreceiving portion. One light receiving portion receives dispersed light,and thus it is possible that the influence of a deviation between thelight receiving portions is ignored compared to a configuration in whicha plurality of the light receiving portions receive the light.

In the printing apparatus of the aspect, the color measurement portionmay include a wavelength variable interference filter which controls agap between reflection films facing each other in Q stages (Q ismultiple number), and a light receiving portion which receivestransmitted light from the wavelength variable interference filter, andthe time Tm may be expressed using an expression as follows:

Tm=Te(Q−1)+Tr·Q

Here, Te is an average time (seconds) necessary for changing the gaponce in a control of the gap in the Q stages, and Tr is a time (seconds)taken for receiving the transmitted light using the light receivingportion.

In addition, the invention can be realized in a printing apparatus inthe following aspect. That is, a printing apparatus of another aspect ofthe invention includes a printing portion that prints a color chart inwhich a plurality of patches are arranged in a first direction and in asecond direction different from the first direction, a color measurementportion that applies a spot of light to the color chart, and measures acolor of each of the plurality of the patches using reflected light fromthe spot, a carriage that includes the printing portion and the colormeasurement portion mounted thereon, and a relative movement portionthat relatively moves the carriage with respect to the color chart, inwhich when a width in the first direction in each of the plurality ofthe patches is set to Wp (m), a time Tall (seconds) necessary formeasuring a color of each of the plurality of the patches is expressedusing an expression as follows, and the width of the patch is set to aminimum value for the time Tall,

Tall=(Nall·Wp·Tm)(W−D)/{W(Wp−D)}+Tnl{(Nall·Wp/W)−1}

Here, Nall is a total number of the patches, Tm is a time (seconds)necessary for measuring the color of one of the plurality of patches byrelatively moving the carriage in the first direction with respect tothe color chart, W is a width (m) of the color chart in the firstdirection, D is a width (m) of the spot in the first direction, and Tnlis a time (seconds) necessary for the carriage to relatively move adistance of one row in the second direction with respect to theplurality of patches.

According to the printing apparatus of the aspect, since the width Wp ofthe patch in the first direction is set to a value in which the timeTall (seconds) necessary for measuring the color of the patch is aminimum value, a process in which the width of the patch is measuredbased on an actual result of measured colors is not needed. Therefore,loss amount of the ink can be reduced and manufacturing time can beminimized.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a view illustrating a schematic configuration of a printingapparatus according to an embodiment.

FIG. 2 is a view illustrating a configuration of a color measurementportion in the printing apparatus.

FIG. 3 is a view illustrating a configuration of an optical filterdevice in the color measurement portion.

FIGS. 4A to 4C are diagrams illustrating a color measurement passage ofa color chart using the color measurement portion.

FIG. 5 is a diagram illustrating characteristics of a function of theentire time for color measurement in which a width of a patch is set toan argument.

FIGS. 6A and 6B are diagrams illustrating an operation of the opticalfilter device, and the like at the time of measuring a color of thepatch.

FIGS. 7A to 7E are diagrams illustrating a relationship between a movingsection between patches and an initialization section.

FIG. 8 is a diagram for describing a diameter of a spot.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the embodiment of the invention will be described withreference to drawings.

FIG. 1 is a perspective view illustrating a schematic configuration of aprinting apparatus.

As illustrated in FIG. 1, a printing apparatus 1 includes a movingmechanism 6 which moves (reciprocates) a carriage 20 in a main scanningdirection (X direction, and first direction).

The moving mechanism 6 includes a carriage motor 61 which moves thecarriage 20, a carriage guide shaft 62 in which both ends thereof arefixed, and a timing belt 63 which is substantially parallel to thecarriage guide shaft 62 and is driven by the carriage motor 61.

The carriage 20 is reciprocatedly supported by the carriage guide shaft62, and is fixed to a part of the timing belt 63. For this reason, whenthe timing belt 63 is forwardly and backwardly driven by the carriagemotor 61, the carriage 20 is guided using the carriage guide shaft 62and is reciprocated.

In the carriage 20, a discharging portion 30 and a color measurementportion 40 are mounted. The discharging portion 30 is a printing portionincluding multiple nozzles provided on a part thereof facing a medium Psuch as paper, which respectively eject ink in a Z direction. Inaddition, the discharging portion 30 is schematically divided into fourblocks for color printing. Each of the blocks respectively ejects black(Bk) ink, cyan (C) ink, magenta (M) ink, and yellow (Y) ink.

In addition, the color measurement portion 40 measures a color of animage (color chart) which is formed on the medium P by the dischargingportion 30 as described later.

Also, in the carriage 20, a control signal is supplied to thedischarging portion 30 or a driving signal supplied to the colormeasurement portion 40 from a main substrate (not illustrated) throughthe flexible cable 190, and a detecting signal from the colormeasurement portion 40 is supplied to the main substrate.

The printing apparatus 1 includes a transporting mechanism 7 whichtransports the medium P on a platen 70. The transporting mechanism 7includes a transporting motor 71, which is a driving source, and atransporting roller 72 which transports the medium P in a sub scanningdirection (Y direction, and second direction) using the transportingmotor 71.

In such a configuration, the medium P is repeatedly transported by thetransporting mechanism 7 while the nozzles of the discharging portion 30eject the ink in accordance with print data according to main-scanningof the carriage 20, and thus an image (including letters, figures, colorcharts, and the like) is formed a surface of the medium P.

In addition, the printing apparatus 1 includes a color measurementfunction for measuring a color in a color chart which is formed on themedium P in accordance with predetermined data. The color measurementfunction is, for example, used for a calibration in which a colordisplayed using data of the measured color becomes a color defined bypredetermined print data described above, or used for making a colorprofile.

The color chart is a color chart in which multiple colors patches asdescribed later are printed in a matrix shape onto the medium P. Thecolor measurement is performed by transporting the medium P, on whichthe color chart is formed, in the Y direction while a color measurementportion 40 mounted on the carriage 20 is forwardly and backwardly movedin a X direction.

FIG. 2 is a view illustrating a configuration of the color measurementportion 40, and particularly, illustrating an example of an opticalpath.

As illustrated in FIG. 2, the color measurement portion 40 is configuredto have a light source 410, a collimate lens 412, a reflection mirror414, a bandpass filter 416, an optical filter device 420, and a lightreceiving portion 430, and these are provided in a rectangular shape ofa case 401 in an internal cavity.

In the case 401, an opening portion 418 is provided on a surface 402facing the medium P.

The light source 410 is, for example, a white LED, and emits light so tobe distributed over a wavelength region, which is at least a target tobe measured. The collimate lens 412 emits the light which is exit fromthe light source 410, as light beams substantially parallel to eachother.

The light exit from the condenser lens 412 passes through the openingportion 418, and is applied as a spot having a diameter D(m) onto themedium P facing the surface 402.

The reflection mirror 414 is a concave surface mirror which reflects andcollects the light, which is reflected to the medium P and is passedthrough the opening portion 418, to the optical filter device 420 andthe light receiving portion 430. The bandpass filter 416 shields harmfullight except the wavelength having colors which are targets to bemeasured among the light beams which are reflected from the reflectionmirror 414 and incident to the optical filter device 420.

The optical filter device 420 includes two variable reflection filmsincluding a gap therebetween, and transmits light having a specificwavelength out of light beams passing through the bandpass filter 416 byreflecting and interfering of the reflection films. The gap between thetwo reflection films in the optical filter device 420 is controlled by avoltage of the driving signal supplied through, for example, theflexible cable 190.

Although the light receiving portion 430 is not particularlyillustrated, it includes a photodiode which converts the light havingthe specific wavelength passing through the optical filter device 420into current, and a conversion circuit which converts the current due tothe photodiode into the voltage.

FIG. 3 is a view illustrating a configuration of the optical filterdevice 420.

As illustrated in FIG. 3, the optical filter device 420 includes ahousing 601 and a wavelength variable interference filter 5.

Among these, the housing 601 includes a base substrate 610 and a lid 620for sealing which constitutes an internal space between the lid 620 andthe base substrate 610.

In the base substrate 610, a light passage hole 611 corresponding to acircular light transmission region when viewed from the top in a Zdirection is provided, and a cover glass 630 having a diameter largerthan the light passage hole 611 is mounted on a surface opposite the lid620. In the same manner, in the lid 620, a light passage hole 621corresponding to the light transmission region is provided, and a coverglass 640 having a diameter larger than the light passage hole 621 ismounted on a surface opposite the base substrate 610.

The wavelength variable interference filter 5 includes a substrate 51fixed by a holding member 58 with respect to the lid 620, and asubstrate 52 bonded to the substrate 51.

The substrates 51 and 52 are made of glass, or the like, and have lighttransmissive properties. In a surface facing the substrate 52 in thesubstrate 51, a reflection film 53 includes the center of a lighttransmissive region, and is provided in a circular shape when viewedfrom the top. Meanwhile, on the surface facing the substrate 51 in thesubstrate 52, the reflection film 54 is provided to face the reflectionfilm 53 and to maintain the gap. Moreover, in order to increase thereflectivity of the reflection films 53 and 54, silver, an alloy whichincludes silver as a main component, or the like, is used for thesefilms.

In the optical filter device 420, the light incident from the coverglass 640 side is repeatedly reflected between the reflection films 53and 54, light having a wavelength which is as great as an integer timesa distance corresponding to twice the gap, is applied to the cover glass630 side.

In the optical filter device 420, a diaphragm 522 is provided on asurface opposite a surface facing the substrate 51 so as to face anouter circumferential edge of the light passage hole 611, outside aregion on which the reflection film 54 is provided in the substrate 52when viewed from the top.

In the substrate 52, in the surface facing the substrate 51, ring shapedelectrodes 564 when viewed from the top are formed on an inner sidebetween the diaphragm 522 and outside the reflection film 54. In thesubstrate 51, an electrode 563 having the same ring shape as theelectrode 564 is formed on the surface facing the substrate 52 so as toface the electrode 564.

In the substrate 52, the diaphragm 522 is easily bent compared to otherparts, when a driving signal is applied to the electrodes 563 and 564,an electrostatic attraction force is generated in accordance with apotential difference between the electrodes 563 and 564. For thisreason, a region inside the diaphragm 522 is adjacent to the substrate51 side, and the gap between the reflection films 53 and 54 decreases inaccordance with the potential difference. Meanwhile, when a drivingsignal is stopped to apply to the electrodes 563 and 564, the gapbetween the reflection films 53 and 54 returns to a former state.

For this reason, in the optical filter device 420, the gap between thereflection films 53 and 54 can be controlled using a voltage of thedriving signal applied to the electrodes 563 and 564, the wavelength ofthe light, which is exit from the cover glass 630, out of the lightbeams exit from the cover glass 640, can be selected.

While the voltage of the driving signal applied to the optical filterdevice 420 is changed, that is, while the wavelength of the lightextracted from the wavelength variable interference filter 5 is changed,a voltage output from the light receiving portion 430 is obtained, andthus a light intensity distribution with respect to a wavelength isobtained. In other words, disperses a plurality of wavelengths of thelight in chronological order, and a spectrum intensity thereof isdetected. In addition, the spectrum intensity is detected by one lightreceiving portion 430, and the influence of a deviation between thelight receiving portions can be ignored compared to a configuration inwhich the spectrum intensity having different wavelength of multiplelight receiving portions is detected.

FIGS. 4A to 4C are diagrams for describing the color chart formed on themedium P, and color measurement passages of the color chart.

As illustrated in FIG. 4A, the discharging portion 30 ejects the ink sothat the patches having multiple colors different from each other arearranged in a matrix shape onto the medium P, and thus the color chartis formed thereon. Here, a distance (width) of the color chart in the Xdirection which is a scanning direction of the carriage is set to W (m),and a width of the one color patch is set to Wp (m).

As described above, a spot of the light, which is exit from the colormeasurement portion 40 and applied to the medium P, has a diameter D.When the spot is applied to a boundary of the patch, the spot is appliedto both sides of the adjacent patches, and thus the color thereof cannotbe accurately measured. In the same manner, when the spot is applied toan end portion of the color chart, the spot is applied to the patch anda medium P on which the color chart is not formed, and thus the colorthereof cannot be accurately measured.

For details, when the center of the spot is applied in a range from oneend toward a negative side of the X direction to a point where only aradius D/2 of the spot is away from a positive side of the X directionin any patch, and a range from the other end toward the positive side ofthe X direction to a point where only the D/2 of the spot is away fromthe negative side of the X direction, a color of the patch cannot beaccurately measured.

In other words, when the center of the spot in the patch is applied to apoint other than these ranges, the color of the patch can be accuratelymeasured. A distance where the color of the patch can be measured, is(Wp-D) which is a subtraction of the diameter D of the spot from a widthWp of the patch. The wavelength of the light passing through thewavelength variable interference filter 5 needs to be changed using thevoltage of the driving signal in a period where the center of the spotmoves the distance (Wp−D) in the X direction by the carriage 20.

Here, for the sake of convenience, time for measuring the color of onepatch by the color measurement portion 40 is set to Tm (seconds). Inthis example, when the time Tm is set to time when the center of thespot moves the distance (Wp−D), a movement velocity V of the carriage(spot) can be expressed as Expression (1) described below.

V=(Wp−D)/Tm  (1)

Next, regarding an arrangement of the patches in the color chart, anarrangement in the X direction is considered as a “column”, and anarrangement in the Y direction is considered as a “row”. The number ofthe column Nc of the patch constituting one row can be generallyexpressed as Expression (2) described below.

Nc=W/Wp  (2)

Moreover, FIGS. 4A to 4C are examples in which the number of the patchesin a column is “five”.

In addition, when a total number (the number of colors) of the patchesconstituting the color chart is set to Nall, a row number L of the colorchart can be generally expressed using a value obtained when dividingthe total number Nall by the number of the column Nc, that is, can beexpressed as Expression (3) described below.

L=Nall/Nc  (3)

When Nc of Expression (2) is substituted for NC of Expression (3),Expression (3) can be expressed as Expression (4) described below.

L=(Nall·Wp)/W  (4)

Moreover, FIGS. 4A to 4C are examples in which the number of rows L ofthe color chart is “4”.

In order to measure the colors of all patches of such a color chart, themedium P is necessary to be transported in the Y direction while thecarriage 20 is positively or negatively moved in the X direction so thatthe spot of the light exit from the color measurement portion 40 movesalong a passage illustrated by a straight thick line in FIG. 4A.

Such a passage can be divided into L numbers of the passage necessaryfor moving the carriage 20 as illustrated in FIG. 4B, and (L−1) numbersof the passage in response to transporting of the medium P by thetransporting mechanism 7 as illustrated in FIG. 4C.

Here, it is considered that time Tall (seconds) necessary for measuringthe colors of all patches in the color chart is reduced. The time Tallcan be expressed by adding the time Tc (seconds) necessary for followingthe passage illustrated in FIG. 4B to the time Td (seconds) necessaryfor following the passage illustrated in FIG. 4C. That is, the time Tallcan be expressed as Expression (5).

Tall=Tc+Td  (5)

First, the time Tc is expressed as L (rows number) times of a time whichis taken for moving the carriage 20 the distance (W−D) at a velocity V.Therefore, the time Tc can be expressed as Expression (6) describedbelow.

Tc=L(W−D)/V  (6)

When Expression (6) is expressed as Expression (7) described below usingExpression (1) and Expression (4).

Tc=(Nall·Wp·Tm)(W−D)/{W(Wp−D)}  (7)

Next, the time Td is (L−1) times of time Tnl for transporting the mediumP a distance of one row in the Y direction when the carriage 20 reachesone end of the color chart. Therefore, the time Td can be described asExpression (8) described below.

Td=Tnl(L−1)  (8)

When L of Expression (4) is substituted for L of Expression (8),Expression (8) can be described as Expression (9) described below.

Td=Tnl{(Nall−Wp/W)−1}  (9)

However, the time Tall in Expression (5) can be described as Expression(10) described below using Expression (7) and Expression (9).

Tall=(Nall·Wp·Tm)(W−D)/{W(Wp−D)}+Tnl{(Nall−Wp/W)−1}  (10)

Here, in a case in which the time Tall has the width Wp of the patch asargument, and the other value is considered as a constant function, thefunction is described to protrude from the bottom as illustrated in FIG.5, and is expressed as a minimum value Tall_min when the width Wp isWp0. The value Wp0 at this time is described as Expression (11)described below.

Wp0=D+{(D·Tm/Tnl)·(W−D)}^(1/2)  (11)

Therefore, the width Wp of the patch constituting the color chart isoptimized as Wp0 expressed using Expression (11), and thus themeasurement time of the color in the color chart can be minimized.

As characteristics illustrated in FIG. 5, the function is rapidlyincreased in a negative side (left side) of the minimum value Tall_min,but is slowly increased in a positive side (right side) relatively. Inother words, when the width Wp is even slightly smaller than the valueWp0, the time Tall is greatly increased with respect to the minimumvalue Tall_min; however, even when the width Wp is slightly greater thanthe value Wp0, the time Tall is slightly increased with respect to theminimum value Tall_min.

In order to minimize the time Tall necessary for measuring the color ofall patches in the color chart, the width Wp of the patch in the colorchart may be set to the value Wp0; however, even when the width W isslightly greater than the value Wp0, a slight increase of the time Tallcan be allowable. Specifically, an increase in the time Tall can beacceptable as long as the width W is approximately the value Wp0+10% orsmaller.

FIG. 6A is a diagram illustrating an aspect of the movement of the spotof the light, which is exit from the color measurement portion 40 to themedium P when the color of the patch is measured. Also, FIG. 6Aillustrates the aspect in which the spot moves in order of the patches(N−1), N, and (N+1). In addition, regarding a position of the spot, thecenter of the spot will be described for the sake of convenience.

As described above, when a part of the spot is applied to a boundary ofthe patch, for details, when the position (center) of the spot is withina range to be described below in FIG. 6A, the color cannot be accuratelymeasured. That is, the range is a range from a forward point P1 to abackward point P3 in a transportation direction as a radius D/2 of thespot based on a point P2 which is a boundary between the patch (N−1) andthe patch N, and a range from a forward point P4 to a backward point P6in a transportation direction of as the radius D/2 of the spot based ona point P5 which is a boundary between the patch (N+1) and the patch N.Moreover, there is a case in which a range from a forward point to therearward point as the radius of the spot based on the boundary of thepatch is set to a moving section between the patches (or time). Inaddition, a distance of the moving section between the patches describedabove is a diameter D of the spot, and movement time between the patchesis D/V.

In other words, regarding the patch N, it means that the color of thepatch N can be accurately measured when a position of the spot is withina range from the point P3 to the point P4. Also, a distance from thepoint P3 to the point P4 is (Wp−D) as described above.

FIG. 6B is a diagram illustrating a movement of the spot correspondingto a change of the wavelength of the light which transmits thewavelength variable interference filter 5 in the optical filter device420. In the optical filter device 420, when one color of the patch ismeasured, the wavelength of the light (transmitted light wavelength)exit from the wavelength variable interference filter 5 is sequentiallycontrolled through 16 stages, for example, from 700 nm (first value) to400 nm (second value), and the light receiving portion 430 receives thetransmitted light from the wavelength variable interference filter 5 atthis time. Specifically, the driving signal applied to the wavelengthvariable interference filter 5 is changed by the voltage correspondingto the transmitted light wavelength, and thus the gap between thereflection films 53 and 54 is controlled in stages from a maximum valuecorresponding to the transmitted light wavelength of 700 nm to a minimumvalue corresponding to the transmitted light wavelength of 400 nm,therefore, the light receiving portion 430 detects the intensity(spectrum intensity) of the transmitted light of the wavelength variableinterference filter 5 in each stage.

The time t1 to the time t2 illustrated in FIG. 6B is time for detectingthe spectrum intensity the transmitted light wavelength of 700 nm. Thetime t2 to the time t3 is time for detecting the spectrum intensity ofthe wavelength reduced as the transmitted light wavelength in a firststage from 700 nm. The time t3 to the time t4 is time for detecting thespectrum intensity of the wavelength reduced as the transmitted lightwavelength in a second stage from 700 nm. After that, in the samemanner, the time t16 to the time tb is a time for detecting the spectrumintensity of 400 nm of the transmitted light wavelength which is reducedin 16th stages from 700 nm.

Also, in this example, the time Tm necessary for measuring the color ofone patch using the color measurement portion 40 can be generallyexpressed as Expression (12) described below from a point of view ofcontrolling the wavelength variable interference filter 5.

Tm=Te(Q−1)+Tr·Q  (12)

In Expression (12), Q indicates the number of stages when the gap iscontrolled, that is, the number of wavelengths being measured, and is“16” in the example of the drawing. Te indicates an average time(seconds) necessary for controlling the gap corresponding to thewavelength in the stage to be a target until stabilized. Moreover, sincea changed amount of the gap is different in each stage, the time Te isset to an average value. In addition, regarding the initial 700 nm, thegap after the initialization period elapsed is used as it is, and a timewhen the gap corresponding to the wavelength of 700 nm is controlleduntil stabilized is zero.

Meanwhile, in the optical filter device 420, the transmitted lightwavelength is changed to 400 nm, and the intensity of the light of thewavelength is output from the light receiving portion 430, and then aninitialization process for controlling (initializing) the value of thegap is performed so that the transmitted light wavelength becomes 700 nmwith respect to measuring the color of next patch.

Initializing the transmitted light wavelength as 700 nm means that thegap is returned from the minimum value to the maximum value (so calledreturning driving), and a changed amount of the gap is great. For thisreason, at the time of returning driving, as illustrated in the drawing,the transmitted light wavelength is taken long time until becomesstabilized and converged. For details, for example, at the time to (tb),even when the gap is controlled from a value when the transmitted lightwavelength corresponds to 400 nm to the initial value when thetransmitted light wavelength corresponds to 700 nm, the transmittedlight wavelength is not immediately stabilized to 700 nm, and it takessome time for converging the transmitted light wavelength within thethreshold th with respect to 700 nm. Also, time from the time ta whenthe gap is controlled to the initial value corresponding to 700 nm ofthe transmitted light wavelength to time when an actual transmittedlight wavelength is converged within the threshold th with respect to700 nm, is referred to as an initialization period, and a section wherethe spot moves in the initialization period is referred to as aninitialization section. In the drawings, the initialization period formeasuring the color of the patch N is expressed using Tt between thetime ta to the time t1.

In the initialization period, the transmitted light wavelength of thewavelength variable interference filter 5 is changed so as not to bestabilized, whereby it is not appropriate to measure the color of thepatch.

In the embodiment, since the moving section between the patches (forexample, point P1 to point P3) where the spot is applied to both sidesof the adjacent patches and cannot be accurately measured the color, andcoincides with the initialization period Tt which is not appropriated tomeasure the color so as not to stabilize the transmitted lightwavelength from the wavelength variable interference filter 5, themovement of the spot with respect to the patch in the color chart iscontrolled at a suitable timing by the wavelength variable interferencefilter 5 in the optical filter device 420. For this reason, in theembodiment, a delay due to returning driving is suppressed to beminimized, and thus it is considered that the time taken for measuringthe color can be reduced by securing accuracy of the color measurement.

In addition, in the embodiment, there is an example in which Dindicating a distance between the moving section between the patches(point P1 to point P3) coincides with the initialization section wherethe spot moves to the initialization period Tt; however, one of thesemay be partially overlapped with the other.

FIGS. 7A to 7E are diagrams illustrating an example of a relationship inwhich the moving section between the patches and the initializationsection are partially overlapped with each other.

First, FIG. 7A illustrates an example in which the moving sectionbetween the patches (point P1 to point P3) coincides with theinitialization section Lt.

FIG. 7B illustrates an example in which the initialization section Lt ispreceded before the moving section between the patches. In this case,since the initialization process starts before the center of the spot isapplied to the moving section between the patches, by that amount,compared to a case of FIG. 7A, the distance (Wp−D) which can be used formeasuring the color of the patch is eroded.

Reversely, FIG. 7C exemplifies a case in which the initializationsection Lt is preceded after the moving section between the patches. Inthis case, even when the center of the spot is deviated from the movingsection between the patches, the initialization process continues.

FIG. 7D exemplifies a case in which the moving section between thepatches is included in the initialization section Lt, and a case whenthe initialization section Lt is taken long with respect to the diameterD of the spot (when time is needed for initialization process).Reversely, FIG. 7E illustrates an example in which the initializationsection Lt is included in the moving section between the patches, andthe initialization section is reduced with respect to the diameter D ofthe spot.

In addition, in the embodiment, regarding the wavelength variableinterference filter 5, the transmitted light wavelength is changed to bereduced from 700 nm to 400 nm; however, reversely, the transmitted lightwavelength is changed to be increased from 400 nm to 700 nm, that is,the gap may be changed in stages from being narrowed to widened.

The initialization process of this configuration means a process inwhich the gap is controlled as a value corresponding to 400 nm of thetransmitted light wavelength.

In the embodiment, in a first row of the color chart, the color ismeasured by moving the carriage 20 in the X direction with respect tothe medium P; however, a first row of the color chart is set to the Ydirection, the carriage 20 is fixed, and the color may be measured bytransporting the medium P in the Y direction, on which the color chartis formed. The point is that, at the time of measuring the color, thecarriage 20 and the color chart may be relatively moved in a directionwhere the first row of the patch is arranged.

In the embodiment, the spot of the light being applied to the colorchart is described as a circular shape; however, the spot may not be acircular shape due to an aberration of the collimate lens 412, not beingparallel of the surface 402 and the color chart to each other, or thelike. Regarding the spot in a case of not circular shape, as illustratedin FIG. 8, the width of the spot in the X direction (movement directionof the carriage 20) may be considered as D.

The entire disclosure of Japanese Patent Application No. 2014-258514filed on Dec. 22, 2014 is expressly incorporated by reference herein.

What is claimed is:
 1. A printing apparatus comprising: a printingportion that prints a color chart in which a plurality of patches arearranged in a first direction and in a second direction different fromthe first direction; a color measurement portion that applies a spot oflight to the color chart, and measures a color of each of the pluralityof the patches using reflected light from the spot; a carriage on whichthe printing portion and the color measurement portion are mounted; anda relative movement portion that relatively moves the carriage withrespect to the color chart, wherein a width Wp (m) in the firstdirection in each of the plurality of the patches is expressed using anexpression as follows:Wp=D+{(D·Tm/Tnl)·(W−D)}^(1/2) here, D is a width (m) of the spot in thefirst direction, Tm is a time (seconds) for measuring the color of oneof the plurality of patches by relatively moving the carriage in thefirst direction with respect to the color chart, Tnl is a time (seconds)for the carriage to relatively move a distance of one row in the seconddirection with respect to the plurality of patches, and W is a width (m)of the color chart in the first direction.
 2. The printing apparatusaccording to claim 1, wherein the color measurement portion disperses aplurality of wavelengths of the light in chronological order.
 3. Theprinting apparatus according to claim 2, wherein the color measurementportion receives the dispersed light using one light receiving portion.4. The printing apparatus according to claim 1, wherein the colormeasurement portion includes a wavelength variable interference filterwhich controls a gap between a first reflection film and a secondreflection film facing to the first reflection film in Q stages (Q ismultiple number), and a light receiving portion which receivestransmitted light from the wavelength variable interference filter, andwherein the time Tm is expressed using an expression as follows:Tm=Te(Q−1)+Tr·Q here, Te is an average time (seconds) for changing thegap once in a control of the gap in the Q stages, and Tr is a time(seconds) taken for receiving the transmitted light using the lightreceiving portion.
 5. A printing apparatus comprising: a printingportion that prints a color chart in which a plurality of patches arearranged in a first direction and in a second direction different fromthe first direction; a color measurement portion that applies a spot oflight to the color chart, and measures a color of each of the pluralityof the patches using reflected light from the spot; a carriage on whichthe printing portion and the color measurement portion are mounted; anda relative movement portion that relatively moves the carriage withrespect to the color chart, wherein when a width in the first directionin each of the plurality of the patches is set to Wp (m), a time Tall(seconds) for measuring the color of each of the plurality of patches isexpressed using an expression as follows, in which the width of thepatch is set to a minimum value for the time Tall,Tall=(Nall·Wp·Tm)(W−D)/{W(Wp−D)}+Tnl{(Nall·Wp/W)−1} here, Nall is atotal number of the patches, Tm is a time (seconds) for measuring thecolor of one of the plurality of patches by relatively moving thecarriage in the first direction with respect to the color chart, W is awidth (m) of the color chart in the first direction, D is a width (m) ofthe spot in the first direction, and Tnl is a time (seconds) for thecarriage to relatively move a distance of one row in the seconddirection with respect to the plurality of patches.